Chicks eating their sand bath?

I thought I'd give my 3-week-old chicks a treat and put some sand (mixed with a bit of DE) in their brooder and all they seem to do with it is eat it. Yuck. I thought I saw one of my chicks trying to give herself a sand bath in the pine bedding crumbs, which is why I put the sand in there to begin with.

So, will it hurt them to eat the sand? I know it's natural for them to take in grit, but a tummy full of it seems a little excessive. Is it a waste to put it in there, or will they eventually get the hang of it?

Well, their sand bath is gone at any rate. I think I added too much DE to it, and it was causing so much dust in the house it was making us all choke. They'll just have to live without it until they move outside I gave them a couple dandylion flowers to play with to make it up to them